Power actuated vehicle closure and release door latch systems use a motor drive unit, which moves an item such as a lever, housed in a latch body, from a rest position to a maximum travel position. The item or lever is generally connected to or operatively coupled to a claw of the latch via a gear train or other equivalent device or system such that as the lever or item is moved between its rest position and its maximum travel position a corresponding desired movement of the claw is also achieved. The claw when rotated or moved engages and retains a striker thereby closing or holding an associated vehicle door in a closed position.
In order to move or rotate the claw sufficiently in the desired range of movement, the lever or item operatively coupled to the claw must also move in a desired range or angle of movement to cause the required movement of the claw as well as accommodate for applied system loads which are caused by a sealing member of the vehicle door opening that is being closed as well as tolerances generated by the gear train or linkage of the latch. As such, the lever or item driven by the motor must be operated or rotated at an angle within the latch body and have sufficient travel with respect to gears or linkage being driven in order to provide repeatable latching within operable limits. Also, the angle at which this lever or item can be operated is limited physically by adjacent structures and mechanisms within the latch body. To change the gear ratio in order to increase the movement of a final gear operatively coupled to the claw may require increasing a length of a crank arm coupled to the final gear as well as unacceptably increase the load on the lever, the crank arm and the motor drive.
Accordingly, it is desirable to provide a power drive vehicle latch assembly that is able to provide a desired range of claw movement with a desired closing force via a range of movement of a lever in the latch without any appreciable change in a crank arm length or loading on the lever, crank arm or motor drive.